OFFSET
0,2
COMMENTS
The row lengths sequence of this array is 3*n+1 = A016777(n).
For the coefficient array of S(n,x)^3 see A219240. The present array is the odd part of the bisection of that one divided by x^3.
The row polynomials in powers of x^2 are (S(2*n+1,x)/x)^3 = sum(a(n,m)*x^(2*m), m=0..3*n), n >= 0. The o.g.f. for these row polynomials is GS3odd(x,z) = ((z+1)^2 +2*z*(x^2-3))/ (((z+1)^2-z*x^2)*((z+1)^2-z*x^2*(x^2-3)^2)). This is obtained from the odd part of the bisection of the o.g.f. for A219240.
FORMULA
a(n,m) = [x^m](S(2*n+1,x)/x)^3, n>=0, 0 <= m <= 3*n.
a(n,m) = [x^m]([z^n]GS3odd(x,z)) with GS3odd(x,z) the o.g.f. for the row polynomials in powers of x^2, given in a comment above.
EXAMPLE
The array a(n,m) begins:
n\m 0 1 2 3 4 5 6 7 8 9
0: 1
1: -8 12 -6 1
2: 27 -108 171 -136 57 -12 1
3: -64 480 -1488 2488 -2472 1524 -588 138 -18 1
...
Row n=4: [125 -1500, 7575, -21200, 36690, -41700, 32211, -17184, 6330, -1580, 255, -24, 1],
Row n=5: [-216, 3780, -28098, 117323, -308688, 546864, -680474, 611019, -402264, 195444, -69894, 18153, -3328, 408, -30, 1],
Row n=6: [343, -8232, 84378, -489608, 1809129, -4562292, 8219967, -10918992, 10927077, -8356272, 4923132, -2240256, 784840, -209580, 41853, -6048, 597, -36, 1],
Row n=1: (S(3,x)/x)^3 = -8 + 12*x^2 - 6*x^4 + 1*x^6, with Chebyshev's S polynomial.
CROSSREFS
KEYWORD
sign,easy,tabf
AUTHOR
Wolfdieter Lang, Dec 17 2012
STATUS
approved